var websocket = null;
var isconnected = false;
//ws基本连接
let wsurl = "ws://127.0.0.1:8080/api/websocket/"
//sid，作为用户凭证
let sid = "200"
//判断当前浏览器是否支持WebSocket
if('WebSocket' in window) {
    //改成你的地址
    websocket = new WebSocket(wsurl+sid)
} else {
    alert('当前浏览器不支持websocket!')
}

//连接发生错误的回调方法
websocket.onerror = function() {
    setMessageInnerHTML("WebSocket连接发生错误");
};

//连接成功建立的回调方法
websocket.onopen = function() {
    setMessageInnerHTML("WebSocket连接成功");
    isconnected = true;
}
var U01data, Uidata, Usdata
//接收到消息的回调方法
websocket.onmessage = function(event) {
    console.log(event);
    setMessageInnerHTML(event.data);

}

//连接关闭的回调方法
websocket.onclose = function() {
    setMessageInnerHTML("WebSocket连接关闭");
}

//监听窗口关闭事件，当窗口关闭时，主动去关闭websocket连接，防止连接还没断开就关闭窗口，server端会抛异常。
window.onbeforeunload = function() {
    closeWebSocket();
}

//将消息显示在网页上
function setMessageInnerHTML(innerHTML) {
    document.getElementById('message').innerHTML += innerHTML + '<br/>';
}

//关闭WebSocket连接
function closeWebSocket() {
    isconnected = false;
    websocket.close();
}

//发送消息
function send() {
    var message = document.getElementById('text').value;
    if(isconnected){
        // websocket.send('{"msg":"' + message + '"}');
        websocket.send(message);
    }
    else{
        setMessageInnerHTML("当前未连接websocket!");
        try{
            websocket = new WebSocket(wsurl+sid)
            setMessageInnerHTML("WebSocket重新接成功");
            isconnected = true;
        }
        catch (e) {
            console.log(e.stackTrace)

        }
    }
    setMessageInnerHTML(message + "&#13;");
}